乳酸菌在农业和食品加工中的应用研究进展

乳酸菌是发酵糖类物质的主要终产物为乳酸的细菌总称。常见的乳酸菌包括乳杆菌属(Lactobacillus)、片球菌属(Pediococcus)、明串珠菌属(Leuconostoc)、乳球菌属(Lactococcus)、链球菌属(Streptococcus)和双歧杆菌属(Bifdobacterium)等少数属的种类。许多乳酸菌属于人和动物胃肠道、泌尿生殖道、母乳、口腔等的正常菌群,能产生多种生物活性物质,具有调节肠道菌群平衡、增强机体免疫力、促进机体生长等益生功能,因而乳酸菌具有重要的应用价值。文本综述了乳酸菌在畜禽养殖饲料添加剂、青贮饲料发酵、水产养殖及植物病害防治等领域的应用研究进展,尤其在“饲料禁抗、养殖减抗、产品无抗”的养殖背景下,乳酸菌制剂是替代抗生素的最佳选择。同时也总结了乳酸菌在奶制品、肉制品加工以及植物基饮料、低糖食品和饮料发酵等方面的开发潜力,展望了乳酸菌研究与应用的发展趋势。     

乳酸菌食品级基因表达系统

酸菌是一类重要工业菌株。最近,乳酸菌遗传学和分子生物学的研究取得长足进步,导致发展了乳酸菌食品级基因表达系统。通过介绍乳酸菌食品级基因表达系统的基本要求、食品级选择性标记、食品级诱导物及该系统的研究进展,展示了乳酸菌食品级基因表达系统的建立对研究乳酸菌的基因表达调控和它的深层次的开发利用所具有的重要意义。     

食品级乳酸菌表达系统研究进展

乳酸菌表达系统是近几年发展起来的食品级高效表达系统。乳酸菌具有益生菌特征,因此该表达系统与其他细菌表达系统相比有很多优点。介绍了糖诱导表达系统、噬菌体Φ31爆发式诱导的表达系统、乳链球菌素调控表达系统、温控表达系统等的研究进展,以及这些系统的应用前景。     

产黏乳酸菌的发酵特性研究

通过对2株产黏乳酸球菌的发酵特性比较研究,以感观、酸度、活菌数对数值、培养时间、粘度及乳清析出率为考察指标,结果表明:乳酸球菌Q26具备较好的产黏、产香特性,遗传性质较稳定.通过与乳酸杆菌G18进行发酵应用试验,确定G18和Q26存在共生关系,混合发酵的酸牛乳乳清析出率为0.1％,粘度为4 528mPa·s.通过保质期试验,产品在28、20、4℃下保质期分别为3、6、15d.确定Q26和G18为最佳酸牛乳生产用菌种.     

乳酸菌的抗氧化作用机制

乳酸菌可以作为发酵剂、保鲜剂用于发酵食品的生产和保藏。由于无法进行呼吸产能,乳酸菌在生长过程中会面临氧化胁迫。研究表明,乳酸菌具有一定的抗氧化能力,能清除体内的活性氧分子,并使其保持相对稳定。综述了乳酸菌的抗氧化作用机制,主要从抗氧化酶、维持细胞还原状态、金属离子螯合等方面进行了介绍,以期为深入了解乳酸菌的抗氧化机制以及改善乳酸菌的环境生存能力提供一定的理论参考。     

应用于乳酸菌的非抗生素抗性选择标记系统

 乳酸菌是一类重要的安全型微生物,在免疫载体疫苗开发及食品菌株改良等医疗、食品领域均有广泛的应用.非抗生素抗性选择标记是乳酸菌基因工程菌株构建中必不可少的关键组成部分,也是目前乳酸菌研究的前沿和热点.根据筛选时质粒和受体菌之间的表型关系及特征,主要分为显性选择标记、互补型选择标记、显性/互补型选择标记、双质粒选择标记4大类.其中显性选择标记中的细菌素抗性/免疫性选择标记及互补型选择标记中的糖类选择标记均有较大的发展潜力及应用空间;双质粒选择标记系统构建的筛选过程新颖独特,为整个选择标记系统的发展开辟了新的途径及思路.     

乳酸菌酸胁迫反应机制研究进展

乳酸菌可发酵糖类产生乳酸,并广泛应用于食品、药物和饲料等工业。由于有机酸的积累,乳酸菌大部分的生长代谢都在低pH的酸性环境中进行,具有酸胁迫反应。pH的自我平衡、ATR反应机制、对大分子的保护和修复作用及细胞膜的变化等是乳酸菌酸胁迫反应的主要机制,其中,pH自我平衡包括F0F1-ATPase质子泵、精氨酸脱氨酶途径(ADI)和谷氨酸脱羧酶途径(GAD)等。由此可见,乳酸菌酸胁迫反应机制涉及到基因和蛋白的表达调控等,是非常复杂的网络调控体系。     

乳酸菌的降血糖作用研究进展

目前乳酸菌的防治糖尿病功效已得到广泛认可.本文综述国内外关于乳酸菌应用于临床糖尿病治疗的研究进展,对乳酸菌可能的降血糖作用机理及物质基础进行了分析总结,并对目前存在的安全性问题和今后研究方向进行探讨,希望为糖尿病防治提供新的思路,为开发新型降糖药物提供一定的理论依据.     

乳酸菌冻干保藏相关影响因素的研究进展

乳酸菌在冻干保藏过程中受到多种因素的作用,采取适宜的保护措施,在很大程度上可避免或减轻冷冻干燥对细胞带来的损伤.主要介绍了影响乳酸菌冷冻干燥及保藏相关因素的研究进展,这些因素包括:菌种自身的性质、生长因素、亚致死处理、冻干保护介质和复水条件.     

三种提取乳酸菌中内源性质粒DNA方法的比较

采用3种不同抽提质粒DNA的方法普查了6株不同乳酸菌的内源性质粒DNA,并对3种不同方法进行比较。在相同条件下,琼脂糖凝胶电泳检测的结果显示:效果最佳者为改进的Anderson-Mckay方法,其次为液氮反复冻融方法,最差者为改进的碱裂解方法。为抽提革兰阳性细菌乳酸菌类的内源性质粒DNA提供了行之有效的方法。     

Establishment of a Novel Method of Screening Anti-Allergic Lactic Acid Bacteria

In this study, we attempted to establish a novel method of screening anti-allergic lactic acid bacteria (LAB). We cloned the human histidine decarboxylase (HDC) promoter into the promoter-less pPhi-Yellow-RPL-dest1 vector and established KU812F cells transduced with this vector (pHDCp-Phi-Yellow/KU812F). After adding LAB to these cells, the change in fluorescence intensity was monitored by flow cytometry. After screening, we identified several LAB strains that downregulated HDC promoter activity. Functional analysis of these LAB strains indicated that two LAB strains inhibited histamine release from KU812F cells, indicating that this assay system can be used to screen for anti-allergic LAB in a high-throughput manner.     

Cloning Vectors Based on Cryptic Plasmids Isolated from Lactic Acid Bacteria:Their Characteristics and Potential Applications in Biotechnology

Lactic acid bacteria (LAB) are Gram positive bacteria, widely distributed in nature, and industrially important as they are used in a variety of industrial food fermentations. The use of genetic engineering techniques is an effective means of enhancing the industrial applicability of LAB. However, when using genetic engineering technology, safety becomes an essential factor for the application of improved LAB to the food industry. Cloning and expression systems should be derived preferably from LAB cryptic plasmids that generally encode genes for which functions can be proposed, but no phenotypes can be observed. However, some plasmid-encoded functions have been discovered in cryptic plasmids originating from Lactobacillus, Streptococcus thermophilus, and Pediococcus spp. and can be used as selective marker systems in vector construction. This article presents information concerning LAB cryptic plasmids, and their structures, functions, and applications. A total of 134 cryptic plasmids collated are discussed.     

乳酸菌在抗病原微生物感染中的作用

乳酸菌作为益生菌中主要的一大分类,在食品、医药和饲料行业中具有广泛应用。乳酸菌具有多种重要生理功能,如维持肠道微生态的平衡、促进肠道蠕动消化、抗高血压、降低血清胆固醇、黏附或降解有害物质等。近年来研究表明,乳酸菌能够通过不同机制抑制病原微生物感染。本文就乳酸菌增强宿主固有免疫和适应性免疫、直接抑制病毒和细菌、增强肠道上皮细胞屏障功能等作用机制的相关研究进展进行综述。     

广西传统发酵米粉中乳酸菌的分离鉴定

对广西传统米粉发酵液中的乳酸菌进行分离筛选,获得6株纯培养优势菌株。通过形态学鉴定及16S rDNA序列分析,结果表明其中4株乳酸菌属于戊糖片球菌(Pediococcus pentosaceus),另外2株鉴定为植物乳杆菌(Lactobacillus plantarum)。这2种乳酸菌均为对人类及动物安全的益生菌,该结果将为传统发酵米粉中有益微生物资源的挖掘和利用奠定基础。     

An Alternative Biotechnological Tool for Magnesite Enrichment: Lactic Acid Bacteria Isolated from Soil

Abstract

Calcium carbonate (CaCO₃) is found in different polymorph structures such as aragonite, vaterite, and calcite. The most common and stable form of CaCO₃, calcite, which is abundant in sedimentary rocks as magnesite ore. Magnesite has application areas in many industrial fields including paper, pharmaceutical and refractory materials. Magnesite is theoretically formulated MgCO₃, but contains many impurities (silicium, iron, and also calcite), that limits its usability and applicability. In this research, we aimed to investigate the decalcification possibility of the raw magnesite material through application of Enterococcus feacelis (EF) with CaCO₃ dissolution ability. The exact mechanism of CaCO₃ dissolution was investigated by carbonic anhydrase enzyme assay and HPLC analysis of organic acids produced by EF. Consequently, EF reduced the amount of CaCO₃ from 2.94% to 0.49% which means a reduction (≈83.33%) in the rate of CaCO₃ percentage. As a result of the experiments, it was observed that different organic acids produced by bacteria reacted with CaCO₃ and removed the lime of magnesite ore. The bacteria used in the study did not show any pathogenic properties in rats, thus, it can be used safely for the industrial applications.     

MyD88 but Not TLR2, 4 or 9 Is Essential for IL-12 Induction by Lactic Acid Bacteria

Although lactic acid bacteria (LAB) affect the immune system, for example, having an anti-allergic effect, little is known about the actual mechanisms of immune modulation. Toll-like receptors (TLRs) recognize conserved microbial molecular patterns, and are presumed to be involved in the recognition of LAB. However, there are few detailed reports examining the relationships between TLR and LAB. We measured here production of IL-12, a cytokine considered to play an important role in anti-allergic effects, induced by Lactobacillus paracasei strain KW3110 and other typical LAB by cells from TLR2-, TLR4-, TLR9- and myeloid differentiation factor 88 (MyD88)-deficient mice. Unexpectedly, similar cytokine production from wild-type and TLR2-, 4- and 9-deficient mice was observed. In contrast, cells from MyD88-deficient mice failed to respond to stimulation with LAB. It is therefore concluded that although LAB, including strain KW3110, are not likely to be recognized by TLR2, 4 or 9, MyD88 is essential for the response to these bacteria.     

一组鸡源乳酸菌产乳酸及其耐受特性研究*

研究了12株（K9、D17、C1、C12、D11、D14、C2、D9、K6、C21、D1和D7）分离自肉鸡肠道的乳酸菌的产乳酸能力及其中3株产酸能力强的菌株的耐受特性。12株乳酸菌产乳酸结果表明：12h内,K6产乳酸速度最快,其次为K9和C1,24h时,D17乳酸浓度最高,48h时C1终乳酸浓度最高。K9、D17和C1的耐受试验结果表明：C1菌株耐酸能力最强,pH2时,C1菌株培养3h后还能检测到活菌,D17和K9菌株培养1h后就已经检测不到活菌。在胆盐浓度0．08％-0．40％范围内,C1、D17和K9均有一定的耐受能力,随着胆盐浓度的升高,C1、D17和K9的存活数呈现缓慢的下降趋势。3株菌中D17耐热能力最强,经80％处理后仍有10^4.9／mL存活数,而K9和C1已检测不到活菌;C1对热最敏感,65℃处理后存活数由10^8／mL降为10^3／mL。     

Lactic acid bacteria as a tool for biovanillin production: A review

Vanilla is the most commonly used natural flavoring agent in industries like food, flavoring, medicine, and fragrance. Vanillin can be obtained naturally, chemically, or through a biotechnological process. However, the yield from vanilla pods is low and does not meet market demand, and the use of vanillin produced by chemical synthesis is restricted in the food and pharmaceutical industries. As a result, the biotechnological process is the most efficient and cost-effective method for producing vanillin with consumer-demanding properties while also supporting industrial applications. Toxin-free biovanillin production, based on renewable sources such as industrial wastes or by-products, is a promising approach. In addition, only natural-labeled vanillin is approved for use in the food industry. Accordingly, this review focuses on biovanillin production from lactic acid bacteria (LAB), which is generally recognized as safe (GRAS), and the cost-cutting efforts that are utilized to improve the efficiency of biotransformation of inexpensive and readily available sources. LABs can utilize agro-wastes rich in ferulic acid to produce ferulic acid, which is then employed in vanillin production via fermentation, and various efforts have been applied to enhance the vanillin titer. However, different designs, such as response surface methods, using immobilized cells or pure enzymes for the spontaneous release of vanillin, are strongly advised.     

猪源乳酸菌产乳酸及其抑菌特性研究

研究了5株(L1、12、L3、L5和L7)分离自仔猪肠道的乳酸菌的产乳酸能力及抑菌特性。结果表明：L5菌株产乳酸的速度最快,培养液中乳酸含量最高,L5菌株培养液pH值的下降速度最快,终末pH值最低,而L1菌株产乳酸的速度最慢,培养液乳酸含量最低。5株乳酸菌对大肠杆菌K88、K99、987P、O141和大肠杆菌E1及金黄色葡萄球菌均有不同程度的抑制作用;排除酸的影响后仍有22％～53％抑菌效果;经热处理后保持有92％以上的抑菌效果;蛋白酶处理后保持85％以上的抑菌效果。     

Potentials of Exopolysaccharides from Lactic Acid Bacteria

Recent research in the area of importance of microbes has revealed the immense industrial potential of exopolysaccharides and their derivative oligosaccharides from lactic acid bacteria. However, due to lack of adequate technological knowledge, the exopolysaccharides have remained largely under exploited. In the present review, the enormous potentials of different types of exopolysaccharides from lactic acid bacteria are described. This also summarizes the recent advances in the applications of exopolysaccharides, certain problems associated with their commercial production and the remedies.